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Biochem - Year 1 Biomed > Oxidative Phosphorylation > Flashcards

Oxidative Phosphorylation Flashcards

1
Q

Why is oxygen needed in energy generation

A

Acceptor electrons and H from the electron transport chain

Allows electrons to constantly move down to generate energy for proton movement for atp synthesis

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2
Q

How does electron movement down transport chain cause proton movement to intermembrane

A

Movement is exergonic (releases free energy)

This energy is used to move protons through the electron carriers (as channels)

= create a proton motive force for atp generation

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3
Q

What is the energy generated from electrons called

A

Electron motive force

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4
Q

What 2 factors allow proton motive force to be maintained (to move protons into ATPase

A

Ph gradient (low ph and high electrical potential in intermembrane)

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5
Q

Explain the structure of the mitochondria and why it’s important in oxidative phosphorylation

A

Double membrane

Outer membrane
Intermembrane space
Inner membrane (cristae)
Matrix

Inner membrane is folded to allow many ATPase and ETC to generate more atp

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6
Q

What is the first electron carrier protein in the chain which allows the acceptance of 2 e/H from NADH to FMN

A

NADH oxidoreductase

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7
Q

What does NADH oxidoreductase do (how electrons move to ubiquinone Q)

A

It transfers the 2 electrons from NADH to FMN

FMN2 (reduced) transfers the electrons

To FeS clusters

Electrons from FeS clusters then transferred to Q

Ubiquinone is then reduced = QH2

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8
Q

What is ubiquinone called when reduced by the electrons from Fe s clusters

A

Ubiquinol (alcohol formed)

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9
Q

What are FeS clusters

A

Fe associated with cysteine amino acids SH(thiol)

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10
Q

What does FMN mean and it’s job

A

Flavin mono nucleotide

It accepts electrons from NADH to be reduced

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11
Q

What is the result of the movement of electrons in the NADH oxidoreductase complex

A

4 protons are transported into intermembrane

Further 2 are removed from matrix to reduce ubiquinone (QH2)

Net removal - 6 H+

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12
Q

What are the protons which are not transported to intermembrane but removed from matrix called

A

Chemical protons

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13
Q

What happens with reduced ubiquinol (2 e and 2H)

A

It is oxidised when the electrons move to cytochrome c oxidoreductase complex

Cytochrome c oxidoreductase becomes reductase (accepts 2E and 2H)

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14
Q

What is the consequence of the reduction of the cytochrome c oxidoreductase complex by Q

A

Q is oxidised and recycled back to accept more protons

The electron movement in the oxidoreductase complex causes extra 4H+ pumped out

2H+ removed from matrix completely

Net loss in matrix = -6H

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15
Q

Which shuttle molecule accepts 2 electrons from the cytochrome c reductase complex

A

Cytochrome c shuttle protein

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16
Q

Is ubiquinone a shuttle molecule?

A

Yes, it always stays in membrane (hydrophobic)

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17
Q

What type of prosthetic group allows cytochrome c to accept 1 electron at a time from cytochrome reductase

A

C type haem (contains Fe)

18
Q

Why are 2 ubiquinols (QH2) needed for cytochrome c shuttle protein to accept 2 electrons

A

Because can only accept 1 at a time

19
Q

What is the oxidation and reduction of Q called

A

The Q cycle

20
Q

What occurs once cytochrome c accepts electrons from cytochrome c reductase complex

A

Cytochrome c oxidase catalyses the transfer of electrons and protons from the cytochrome c to O2

4e from cytochrome c and 4H+ from the matrix reduce 02 into H20

21
Q

What does reduction of water by 4 e and 4 h generate

A

Water and exergonic so power to pump 4 more H+ into intermembrane

22
Q

What is the net loss in the cytochrome c oxidase complex

A

8 H+

4 are pumped out due to o2 reduction, 4 are used to reduce water

23
Q

What is the net loss of H+ in the matrix compared to net gain of H+ in the intermembrane

A

Intermembrane = 12H+

Matrix = -16 H

24
Q

What are the 4 complexes in oxidative phosphorylation

A

I = NADH - Q oxidoreductase complex

II= succinate dehydrogenase- Q complex

III= Q - cytochrome oxidoreductase complex

IV= cytochrome c oxidase complex

25
Q

How is FADH2 electrons transported to Q ubiquinone (complex II)

A

Accepted by succinate dehydrogenase which transports the 2E to ubiquinone which is then reduced into ubiquinol

26
Q

What ion is needed by succinate dehydrogenase to accept electrons from FADH2

A

Fe (just like NADH oxidoreductase needs it and also cytochrome c has fe)

27
Q

How does H from the intermembrane space get into ATPase enzyme complex (V)

A

H half channel which is on the intermembrane side of the ATPase

28
Q

What happens when H goes into the ATPase half channel

A

Proton binds to the aspartate (-ve) amino acid on the c ring subunits

This causes the c ring subunit aspartate to become neutral and move into the membrane

(Rotation)

Causing next c ring subunit to be exposed which allows New H to attach

This movement drives rotation

After c ring rotation protons are released through the other half channel and aspartate returns to be negative

29
Q

What does rotation of the c ring cause to rotate (due to addition of H to make aspartate negative)

A

Gamma arm which attaches the c ring with beta and alpha proteins on the other side of ATPase

30
Q

What happens when the gamma Y arm rotates when c ring rotates

A

Causes rotation of the beta and alpha subunits

31
Q

Which out of the beta and alpha proteins on ATPase is bigger

A

Beta

32
Q

What is attached to beta and alpha apart from the gamma Y arm

A

B arm

33
Q

What causes beta arms to move in and out

A

When beta protein goes past it b arm is pushed out

When alpha goes past b arm when Y rotates this causes b arm to move in

34
Q

What does b arm movement in and out cause

A

Kinetic energy which is turned into atp synthesis Adp + pi into atp

35
Q

At the end of oxidative phosphorylation along with glycolysis and Krebs how many ATP and O2 and H20 produced (6 cycles for glucose)

A

ATP = 30 generated

6 O2 are used

6 H2O are generated

36
Q

How many NADH and FADH are present in oxidative phosphorylation

A

10 NADH (4 from glycolysis , 6 from citric cycle)

2 FADH2 from citric cycle

37
Q

Which 3 chemicals can prevent oxidative phosphorylation

A

Carbon monoxide

Cyanide

Salicylate

38
Q

How can carbon monoxide stop oxidative phosphorylation

A

Has high affinity to haemoglobin and binds to FE causing no oxygen into cells

39
Q

How does cyanide stop oxidative phosphorylation

A

Binding to complex 4 (cytochrome c oxidase )

40
Q

How can salicylate stop oxidative phosphorylation

A

Forms pores in membrane so H can move without generating ATP

41
Q

Why is oxidative phosphorylation damaging to the mitochondria

A

Etc oxygen species are reactive and can cause high mutation and error rate in dna of mitochondria

42
Q

What is the difference between cytochrome c coenzyme and ubiquinone Q

A

Q can carry 2 e and 2 H

Cytochrome c only carries 1 via the haem group

Biochem - Year 1 Biomed (21 decks)

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